1. Field of the Invention
The present invention relates to a shelf apparatus which will raise and lower refrigerator's food storage shelves in an analog manner.
2. Description of the Prior Art
In recent years, a great variety of different things are stored in refrigerators. For example, prepared foods are refrigerated in large salad bowls or on plates etc., and large uncut vegetables, fruits or the like are refrigerated just as they are.
In this case, to secure space for storing large items of food and the like, it is necessary to increase the capacity of storage space between one storage shelf and another storage shelf inside a refrigerator (hereinafter, referred to as storage space). In the prior art, in order to increase the capacity of storage space, it is common that a plurality of rails parallel to a horizontal plane provided on opposing side walls of a refrigerator's interior to support storage shelves are employed, and then the positions for inserting the storage shelves are changed.
However, the above-mentioned means of the prior art makes it necessary to first remove all of the food etc. on the storage shelves in order to change the positions at which the storage shelves are inserted, and this is inconvenient.
Furthermore, since each position is fixed for a plurality of rails which support the storage shelves, an increase or decrease in capacity of the storage space becomes uniform, and hence there is a problem of not being able to increase or decrease the capacity corresponding to the size of each food etc.
The U.S. Pat. No. 2841459 discloses a means for solving the above-mentioned problem. This conventional shelf apparatus for a refrigerator comprises shelves arranged inside a refrigerator, frames for holding the shelves, two rails for sustaining the sliding of rollers which are supported at the left and right of the frame, and a jackscrew for fixing the frame at desired positions. The frame holds a nut engaged with the jackscrew and a shaft with a handle for rotating the nut so that they can rotate freely. Furthermore, the rails are vertically installed at the left and right rear of the refrigerator's interior, and the screwjack is vertically installed at the rear center of the refrigerator's interior. Then, the position of the frame for holding the shelf is changed by turning the shaft with a handle, which rotates the nut engaged with the jackscrew, and thereby changes the position of the nut.
The above-mentioned shelf apparatus for a refrigerator has a construction in which the position of the frame for holding the shelf is raised and lowered by the jackscrew installed at the rear center of the refrigerator's interior, and when food is placed on the shelf, particularly when the load is lopsided on either left or right, the shelf tilts to the side on which most of the food is placed and the rollers contact the rails at an angle, so that they do not rotate smoothly, making it necessary to turn the shaft with a handle using a great deal of force. Furthermore, the shaft with a handle, jackscrew and so forth are in the center portion of the shelf, and this structure is comparatively large, it becomes an obstruction to the placement of food on the food storage surface of a lower shelf or the bottom tier.
Furthermore, when a frame reaches the top or bottom of the refrigerator's interior, or when a plurality of them are provided and there are collisions between the frames, and when the dial shaft is over-loaded, there is a problem of the handle causing damage to the shaft.